Location: Crop Production Systems ResearchTitle: Southern corn leaf blight a story worth retelling Author
Submitted to: Agronomy Journal
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 3/13/2017
Publication Date: 5/5/2017
Citation: Bruns, H.A. 2017. Southern corn leaf blight a story worth retelling. Agronomy Journal. 109(4):1-7.
Interpretive Summary: The southern corn leaf blight epidemic of 1970-1971 destroyed 15% of the North American corn crop at a cost of $1.0 billion (US) > $6.0 billion in today’s economy. It was the result to a natural mutation of an existing corn disease, a crop in which >85.0% had a common genetic back ground of Texas male sterile used in growing the seed, and a favorable environment for the fungus to spread. Some areas lost up to 30-50% of their crop with some farms losing 100% of their production. This is considered a warning to the seed industry never to purify the genetics of our crops to such an extent again and to preserve genetic diversity.
Technical Abstract: The Southern Corn Leaf Blight Epidemic of 1970-1971 was one of the most costly disease outbreaks to affect North American agriculture, destroying 15% of the crop at a cost of $1.0 billion (US). It resulted from an over reliance on cytoplasmic Texas male sterile (cms-T) lines in hybrid seed production and a natural mutation of a race of Bipolar maydis that for years was seldom of economic importance. This mutation discovered in the Philippines in 1961 first appeared in the Corn Belt in 1969, damaging not only leaves, but stalks, ears, and developing kernels of hybrids containing cms-T genetics. A favorable environment, combined with > 85% of the hybrids grown being of cms-T genetics set the stage for an epidemic. The cms-T was discontinued in 1971 and hybrid seed production returned to using detasseling for the female parent. This serves as warning to the seed production business never to purify the genetics of our crops to such an extent as this again and to preserve genetic diversity.